A pneumatic tire having a carcass toroidally extending between bead portions has been known. The following patent document 1 proposes a pneumatic tire provided with a bead reinforcing rubber layer on the outer surface in the tire axial direction of the carcass in the bead portion. The bead reinforcing rubber layer controls distortion of the bead portion so that the durability of the bead portion is improved.
The following patent document 2 proposes to form a bead reinforcing rubber layer by a strip winding method so that the shape can be flexibly changed according to a tire size and the like.
In a strip winding method, for example, a target raw (unvulcanized) reinforcing rubber layer is formed by winding a band-like rubber strip, which is unvulcanized and whose width is about 5 to 30 mm, spirally circumferentially of the tire. In the raw reinforcing rubber layer, each rubber strip is integrated by being vulcanized. A reinforcing rubber layer formed through a strip winding method comprises adjacent rubber strip's interfaces. The interfaces extend in the tire circumferential direction along the surface of the reinforcing rubber layer.